ktvu health and science editor revealed how young women may unwittingly be putting themselves in harm's way. >> reporter: it's convenient say many young women. >> it's probably the most convenient place to put it, especially when you go out. you put your money on one breast and your phone on other. >> it's really easy to festival vibration and you can see the call really fast. >> if i'm wearing a dress i slip it in the straps or down in the center. >> reporter: maybe they should talk to tiffany frantz. her mother had misgivings. >> we never took it seriously until after she was diagnosed. >> reporter: tiffany got breast cancer at 21? >> her tumors were exactly where her cell phone had been against her bare skin for six years. >> reporter: surgeons removed tiffany's left breast. >> it's kind of coincidental. >> the dots here are where her tumors developed and her doctors said the destruction matched her cell phone. this imagine shows that the tumors were just under the surface of her skin. >> all this area right here which is where i put my cell phone. >> reporter: jean said she did that